The resignation of Donald Trump’s top economic adviser sent a shudder through markets and prompted alarm among corporate leaders yesterday as business braced for the White House to pursue more protectionist measures.

Leading corporate lobbyists said the departure of Gary Cohn, a centrist force in the White House policy maelstrom, could endanger the economic gains flowing from recent corporate tax cuts and undercut US leadership if it led to more aggressive actions on trade.

Despite the warnings from investors and corporate interests, the administration said it would press on with tariffs on steel and aluminium imports, which are championed by Cohn rivals Peter Navarro, White House trade adviser, and commerce secretary Wilbur Ross.

“We are definitely going to end up with these tariffs and we are going to roll this out very, very quickly,” Steven Mnuchin said yesterday. The Treasury secretary also told Fox Business there would be a process for businesses to seek exceptions from the president.

Mr Cohn’s announcement rattled equity investors, with European markets selling off sharply before recovering; the Hang Seng closed down 1 per cent. The S&P 500 fell as much as 1 per cent in the morning before recovering.

Washington’s biggest business lobby, the US Chamber of Commerce, said it was “very concerned about the increasing prospects of a trade war” following the announced departure of Mr Cohn, a former president of Goldman Sachs who vigorously opposed the tariff measures.

“Alienating our strongest global allies amid high-stakes trade negotiations is not the path to long-term American leadership,” said chamber president Thomas Donohue, urging the administration to refrain from global tariffs that would harm US manufacturers.

The corporate broadsides came at the same time that US Steel delivered a boost to the president, saying it would reopen idled operations at its Granite City Works in Illinois, saying the move was prompted by the promised tariffs.

“This is a dangerous time for trade,” said Steve Moore, a former Trump campaign adviser. He said Mr Cohn was not irreplaceable and Mr Trump’s decision on tariffs had been predictable given his campaign pledges. But he added: “The economy is firing on all cylinders, so why disrupt it with this policy?”